Arthroplasty devices with resorbable component

ABSTRACT

Arthroplasty devices having improved bone in growth to provide a more secure connection within the body. Different embodiments disclosed include devices having threaded intramedullary components, devices configured to receive bone growth promoting substances, devices with resorbable components, and devices configured to reduce shear stress.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit from U.S. Provisional Patent ApplicationSer. No. 60/392,234, filed Jun. 27, 2002 which application isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed in general to arthroplasty devicesand, in particular, to arthroplasty devices which improve bone growthinto said devices.

2. Description of the Related Art

The use of arthroplasty devices to replace damaged or defective jointswithin the body is commonplace in the medical field. The prostheticreplacement of joints has evolved over the years from early relativelycrude models to current prostheses which closely replicate functions andmotions of a natural joint. Prosthetic arthroplasty devices have beenused as replacements for the shoulder, hips, knee, ankle and invertebraldisc.

One problem encountered with prosthetic joints includes movement of theimplant with respect to the patient's bones. This motion oftencompromises fixation. Another problem that occurs is an abnormal stresstransference from the implant to the bone.

The most common method of holding the implant in the bones is“press-fitting” the device into the intramedullary cavity of the bone.This often causes abnormal stress distribution, leading to prematurefailure.

These devices also rely on the ingrowth of the patient's bone to holdthese devices in place. The difficulty of achieving true growth of apatient's bone into a metal prosthesis is a well known problem in thesurgical field.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide anarthroplasty device which has improved bone ingrowth capabilities.

It is a further object of the present invention to provide anarthroplasty device configured to reduce shear stress.

It is a still further object of the present invention to provide anarthroplasty device having a resorbable component which restricts motionin a joint for a period of time to allow for improved bone ingrowth.

It is a still further object of the present invention to provide anarthroplasty device configured to receive bone growth promotingsubstances.

These and other objects and advantages of the present invention will bereadily apparent in the description the follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a lateral view, partly in cross section, of a femur and aprior art impacted femoral component of a hip replacement;

FIG. 2 is a lateral view, partly in cross section, of a femur and anembodiment of the present invention showing a femoral hip replacementdevice having a threaded component;

FIG. 3 is a cross-sectional view of the embodiment of the presentinvention shown in FIG. 2;

FIG. 4 is an exploded view of the device of FIG. 2;

FIGS. 5A–D, taken together, show the sequence of installation of thedevice of FIG. 2;

FIG. 6 is a lateral view, partly in cross section, of the device of FIG.2 which includes a collared rod component;

FIG. 7 is a cross-sectional view of the device of FIG. 2 which includesan antirotation feature;

FIG. 8A is a cross-sectional view of the femur and another embodiment ofthe device of the present invention having an expandable component shownin the contracted position;

FIG. 8B is a cross-sectional view of the device of FIG. 8A showing theexpandable component in the extended position;

FIG. 9A is a lateral view of another embodiment of the presentinvention;

FIG. 9B is a cross-sectional view of the device of FIG. 9A;

FIG. 9C is a cross-sectional view of another version of the device ofFIG. 9A;

FIG. 10A is a lateral view of another embodiment of the presentinvention;

FIG. 10B is a cross-sectional view of the device of FIG. 10A;

FIG. 10C is a different cross-sectional view of the device of FIG. 10A;

FIG. 11A is a lateral view, partly in cross section, of anotherembodiment of the present invention;

FIG. 11B is a lateral view, partly in cross section, of the device ofFIG. 11A after a period of time;

FIG. 11C is a lateral view of another embodiment of the presentinvention;

FIG. 11D is a cross-sectional view of the device of FIG. 11C;

FIG. 11E is a lateral view of another embodiment of the presentinvention;

FIG. 12A is a lateral view of an alternative device according to thepresent invention for use in prosthetic disc replacement shown in theunassembled position;

FIG. 12B is a lateral view of the device of FIG. 12A in the assembledposition;

FIG. 13 is a lateral view of a femoral component according to thepresent invention;

FIG. 14 is a perspective view of another embodiment of the presentinvention;

FIG. 15A is a perspective view of the device of FIG. 14 with a portionof the device removed and a syringe shown for injecting a bone growthpromoting substance into the device;

FIG. 15B is a perspective view of FIG. 15A showing the device of FIG. 14partially filled;

FIG. 16A is a lateral view of a section of the spine showing the deviceof FIG. 14 installed in position between the vertebrae;

FIG. 16B is a lateral view of a drill bit which may be used to create ahole in the device of FIG. 14;

FIG. 17 is a perspective view of an alternative embodiment of the deviceof FIG. 14;

FIG. 18A is an end view of an alternative artificial disc replacementdevice for use in the present invention;

FIG. 18B is a sectional view of the device of FIG. 18A positionedbetween vertebrae of the spine;

FIG. 19 is a perspective view of an acetabular component for use in anembodiment of the present invention;

FIG. 20 is a perspective view of a femoral component for use in anembodiment of the present invention;

FIG. 21 is a perspective view of an alternative acetabular componentsimilar to the device of FIG. 19;

FIG. 22A is a perspective view of an alternative femoral componentsimilar to the device of FIG. 20;

FIG. 22B is a perspective view of another alternative femoral componentsimilar to the devices of FIG. 20 and FIG. 22A;

FIG. 23A is a lateral view of an alternative embodiment of the device ofFIG. 12A;

FIG. 23B is a lateral view of the device of FIG. 23A shown in thedeployed position;

FIG. 23C is a lateral view of an alternative embodiment of the deviceshown in FIG. 23A;

FIG. 23D is a sectional view of the device of FIG. 23C;

FIG. 24A is an exploded view of an alternative embodiment of a deviceaccording to the present invention;

FIG. 24B is a cross-sectional view of the device of FIG. 24A in theassembled position;

FIG. 24C is a cross-sectional view of the device of FIG. 24A installedin the femur;

FIG. 24D is a cross-sectional view of an alternative embodiment thethreaded component shown in FIG. 24A;

FIG. 25A is a cross-sectional view of a device according to the presentinvention installed in the tibia;

FIG. 25B is a cross-sectional view of an alternative embodiment of thedevice of FIG. 25A;

FIG. 26 is a cross-sectional view of a device according to the presentinvention installed in the proximal femur;

FIG. 27A is a cross-sectional view of a device according to the presentinvention installed in the distal femur;

FIG. 27B is a cross-sectional view of an alternative embodiment of thedevice of FIG. 27A installed in the distal femur;

FIG. 28A is an exploded view of a device according to the presentinvention for use in a long bone;

FIG. 28B is a cross-sectional view of the device of FIG. 28A inventioninstalled in a long bone;

and FIG. 28C is a cross-sectional view of an alternative embodiment ofthe device of FIG. 28A.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1. represents a typical prior art impacted femoral component of ahip replacement commonly used in the surgical field today. Referring nowto FIG. 1, there is shown a femoral component 10 having an elongatedtapered portion 12, an extended stem portion 14 for connecting component10 to the prosthetic femoral head, and a textured surface area 16. Inuse, tapered portion 12 is driven into a femur 20 which has beenprepared to receive component 10. Surface area 16 of component 10 isconfigured to encourage bone ingrowth to assist in the permanentattachment of component 10 within femur 20. Surface area 16 may containsmall beads, fibrillar wires or other structures known in the art topromote bone ingrowth. This type of arthroplasty device relies onimpaction of the device into patients' bones for stability.

The difficulty of achieving true growth of a patient's bone into metalprostheses is well known in the medical field. FIGS. 2–4 show a deviceaccording to the present invention which assists in overcoming thisproblem. Femoral hip replacement device, generally designated as 30,includes an upper outer sleeve 32 which contains a textured surface area34, a tubular inner component 36 having a threaded lower portion 38, andan elongated rod component 42 having an outwardly extending stem 44. Inoperation, threaded portion 38 of component 36 engages an internallythreaded area which has been previously incorporated into femur 20.Alternatively, portion 38 may contain self tapping threads forattachment within femur 20. Sleeve 32 is then installed on the tubularportion of component 36 such that it is held against threaded portion 38and the inner walls of femur 20. Elongated rod component 42 is theninserted through tubular component 36 such that it is tightly held inplace by sleeve 32 and femur 20, as can be best seen in FIG. 2.

Although device 30 contains surface area 34 to assist bone ingrowth,threaded section 38 helps to stabilize device 30, as threaded componentsare less likely to allow motion between the device and bone. Boneingrowth, which is dependent upon the surface features of the device andmotion between the device and the bone, is thus facilitated bydecreasing motion between the arthroplasty device and a patient's bone.

The process for installing device 30 is shown in FIGS. 5A–D. Referringnow to FIG. 5A, a tap 50 having a thread cutting end 52 is used to chasethreads within femur 20 in the area in which threaded portion 38 ofcomponent 36 is to be affixed within femur 20. Alternatively, portion 38may be manufactured as a self-tapping device. After this has beenperformed, portion 38 is brought into threaded engagement with femur 20,with tubular portion 36 positioned above the threaded connection (FIG.sleeve 5B). Next, outer sleeve 32 is forced over tubular portion 36until the edge of sleeve 32 contacts threaded portion 38 (FIG. 5C).Finally, elongated rod component 42 is inserted through tubular portion36 captured within sleeve 32 such that outwardly extending stem 44 isproperly positioned for attachment within the prosthetic femoral head.This construction decreases the possibility of motion between device 30and femur 20, potentially enhancing bone ingrowth.

FIG. 6 represents another embodiment of device 30 which a collar 60positioned on rod component 42 between stem 44 and sleeve 32 to aid inthe positioning of device 30 within femur 20. In this embodiment, rodcomponent 42 is inserted through tubular portion 36 within sleeve 32until collar 60 contacts sleeve 32. In this manner, forces within rodcomponent 42 are transferred to sleeve 32 having textured surface 34 forbone ingrowth, adding additional stability to device 30.

FIG. 7 is a sectional view of an alternative embodiment of device 30which adds an anti-rotation feature for additional stability. Referringnow to FIG. 7, rod component 62 contains outwardly extending edges 62 a,62 b. Tubular component 64 contains a pair of channels 64 a, 64 b withinits inner walls corresponding to edges 62 a, 62 b. In this manner, rodcomponent 62 cannot rotate within tubular component 64, addingadditional stability to the arthroplasty device, which potentiallypromotes bone ingrowth. Rod component 62 may also contain a cruciformshape, with tubular component 64 having a corresponding shape.

Square threads, buttress threads, or reverse buttress threads may beused in the embodiments requiring threaded devices, as these decreasehoop stress on the bone. Hoop stress can lead to fracture of the bone.Taper threads may also be used. In addition, the threads can be eitherleft or right handed.

FIGS. 8A–B represent another alternative embodiment for an arthroplastydevice according to the present invention. In this embodiment, anadjustable component 68 having a first section 68 a and a second section68 b which are movable relative to each other by a pair of adjustingscrews 70 is inserted into femur 20 in order to fit a patient's boneanatomy better. Screws 70 are adjustable to shift component 68 between acontracted position (FIG. 8A) and an expanded position (FIG. 8B). Screws70 are adjusted by a corresponding pair of screws 72 which, when turned,control the adjusting motion provided by screws 70. Alternatively, awrench may be used to turn a screw, or gear, which cooperates with atoothed component to force sections 68 a and 68 b apart.

Component 68 is placed into the intramedullary canal of a bone andexpanded. The tighter fit provided by component 68 decreases motionbetween the prosthesis and the patient's bone. Adjustable component 68also allows for compaction of the cancellous bone with the cortical boneinto which the prosthesis device is inserted. Cancellous bone is rich incells that promote bone ingrowth. Prior art impacted devices aregenerally inserted into the cortical bone after the removal of most ofthe cancellous bone. Thus, expanding components such as component 68will aid in the immobilization of the prosthesis and preserve thehealing characteristics of cancellous bone. While the device shown inFIGS. 8A–B show expansion of one component in one direction, multiplecomponents may be used that expand in multiple directions. A torquewrench may be used to control the force and help prevent fracture of thebone into which the device is to be inserted. In addition, shape memorymaterials may be used to change the shape of components within thedevice. For example, a sleeve made of nitinol could be inserted in itscontracted shape and then open to the expanded shape after insertioninto the base.

Alternative expansion mechanisms could be used for component 68. Forexample, a scissor jack-like mechanism or inclined planes could be usedto move the sections to its expanded position. In addition, multiplesections can be used that expand in multiple directions.

In another embodiment, a rod component similar to that shown in FIGS.2–6 is inserted between sections of component 68 in its expandedexpansion. The implanted rod may be held in position within component 68by adding a taper to the interior surfaces of sections 68 a and 68 b.

Upper outer sleeve 32 which contains textured surface area 34 in FIG. 2can be adapted to further enhance bone ingrowth in devices according tothe present invention. FIGS. 9A–C demonstrate several alternativeembodiments which may be used to further promote this growth. Referringnow to FIG. 9A, upper outer sleeve 34 contains a plurality of wells 80along its outer surface which replaces the textured surface. Wells 80are filled with collagen sponges 82 which have been soaked with BaseMorphogenetic Protein (BMP). Sponges 82 are inserted into wells 80 priorto insertion of device 30 into femur 20. In FIG. 9C, sleeve 34 containsa plurality of channels 84 which extend along the length of sleeve 34.In this embodiment, BMP could be injected into channels 84 afterinsertion of device 30, or BMP soaked collagen sponges 82 may be forcedinto channels 84.

Another alternative embodiment of an arthroplasty device according tothe present invention is shown in FIGS. 10A–C. A femoral rod component90 having an outwardly extending stem 92 and a collar stop 94 ininstalled through a sleeve 96 having a textured area 98 for promotingbone ingrowth. The interior of sleeve 96 contains of pair of grooves 100which correspond to a pair of wings 102 extending from the outer surfaceof component 90 such that the interaction of wings 102 and grooves 100allow small amounts of motion between rod component 90 and sleeve 96 todecrease the shear stress on textured area 98 where bone ingrowthoccurs. Shear stress can cause motion between the device and thepatient's bone, decreasing the chance of bone ingrowth. Devices usinganti-rotation features, such as shown in FIG. 10C and FIG. 7, will haverods with varying degrees of version, including antiversion andretroversion.

FIGS. 11A–E show an alternative embodiment of the device according tothe present invention which uses resorbable components to temporarilydecrease or remove the stress on the bone ingrowth surfaces of thedevice. Referring now to FIG. 11A, an arthroplasty device 100 similar tothe device of FIGS. 10A–C is shown, having a femoral rod component 102with a outwardly extending stem 103, a positioning sleeve 104 having atextured area (not shown) for promoting bone growth, and a solid disc106 having an threaded outer surface 108. Disc 106 is initiallypositioned within a femur 20. Disc 106 has been installed into positionwithin femur 20, after its interior has been threaded in the appropriatearea by using a tool similar to that shown in FIG. 5A. Alternatively,outer surface 10B may contain self-tapping threads. Resorbable material110 is threaded into femur 20, contacting disc 106, and then rodcomponent 102 is introduced into sleeve 104. Note that component 102 issupported by resorbable material 110 and not sleeve 104. Preferably,device 100 contains the anti-rotation features shown in FIG. 10C.Additionally, anti-rotation features can also be added between disc 106,resorbable material 110 and the end of rod component 102 for additionalstability. Suitable resorbable materials include a high molecular weightpoly-L-lactic acid (PLLA) polymers, calcium hydroxyapatite, tricalciumphosphate. Other potentially useful resorbable materials includepolydiaoxanone (PDS), oxidized regenerated cellulose and various formsof collagen.

In this relationship, resorbable material 110 temporarily decreases orremoves the stress on the bone ingrowth surfaces of sleeve 104. Theforces on device 100 are transferred from resorbable material 110 to theingrowth surfaces of sleeve 104 as resorbable material 110 disappears.Disc 106 may also contain a through hole 111 to aid in the drainage ofresorbable material 110. This resorption process generally takes months.Bone will grow into the ingrowth area of sleeve 104 while device 100 issupported by resorbable material 108. Eventual transfer of the forces tothe ingrowth area of device 100 is important to prevent bone resorptionthat occurs with stress shielding. Resorbable material 110 may alsotemporarily eliminate movement through device 100. Eliminating movementacross device 100 decreases forces on the bone ingrowth surfaces. Motionthrough device 100 is permitted once resorbable materials 110 hasdissolved, as rod component 102 now contacts sleeve 104, as can be seenin FIG. 11B.

A prosthetic hip device according to the present invention is shown inFIGS. 11C–D. Hip device 112 includes a femoral rod component 114 havingan outwardly extending stem 115, a head 116 mounted on stem 115, aninner acetabular component 117, and an outer acetabular component 118. Aresorbable component 120 is located between component 118 and rodcomponent 114 to restrict motion between the acetabular and femoralcomponents of device 112 until resorbable component 120 disappears,allowing time for bone ingrowth to firmly take hold.

FIG. 11E shows prosthetic disc replacement device 122 according to thepresent invention. Device 122 includes an upper plate 123 and a lowerplate 124 connected by a pivot 125. Resorbable material 126 is placedbetween plates 123 and 124 before insertion of device 122 into aposition between vertebrae of the spine.

FIGS. 12A–B show an alternative embodiment of a prosthetic discreplacement device 130. Device 130 contains an upper plate 131 and alower plate 132. Each plate contains a keel-like ingrowth extensioncomponent 134 attached for rotation through plates 131, 132 at a pivot135. An activation device 136 consisting of a flat plate is also shown.To install device 130, the device is placed between vertebrae in thespine of a patient. Activation device 136 is pushed between plates 131and 132 to force extensions 134 away from plates 131, 132 to affixdevice 130 in its proper location between the vertebrae. Extensions 134are exposed to the cancellous bone of the vertebrae, immobilize device130 and help prevent its extrusion.

FIG. 13 shows another embodiment of a method for restricting motion ofthe prosthesis relative to the bone when using an arthroplasty device.Referring now to FIG. 13, there is shown a femoral component 140positioned within femur 20. Component 140 is held firmly in place by afirst screw 142 which is affixed crosswise through component 140 andfemur 20. A second screw 144 is affixed through component 140 and femur20 in a direction oriented approximately 90° to first screw 142. A guideis preferably removably attached to femur 20 or component 140 to helpdirect a drill bit through femur 20 and to thread screws 142 and 144through the structure. Use of screws 142 and 144 assist in minimizingmotion of component 140 with respect to femur 20, allowing bone ingrowthbetween component 140 and femur 20.

FIG. 14 shows a device which promotes bone ingrowth in a spinal fusionprocedure. Implant 200 consists of a box-like structure having top andbottom surfaces 200 a, 200 b, front and rear surfaces 200 c, 200 d, andside surfaces 200 e, 200 f. In this embodiment, surfaces 200 a and 200 bare essentially parallel, 200 c and 200 d are essentially parallel, and200 e and 200 f are essentially parallel; however, implant 200 canconsist of any shape which will fit between adjacent vertebrae. Surface200 c contains an aperture 202 which allows access to the interior ofimplant 200. Aperture 202 allows for the injection of a bone growthpromoting substance into implant 200. Possible substances includePlatelet Rich Plasma (PRP), bone morphogenetic protein (BMP), orconcentrated leukocytes. Other substances which are available arediscussed in my co-pending patent application Ser. No. 09/897,000, whichapplication is incorporated by reference herein. Although implant 200 ispreferably manufactured from bone, it could also be constructed fromother compatible materials such as metal or polymers. Alternatively, themetal or polymer devices could be filled with bone.

FIGS. 15A–B show how implant 200 can be filled with an appropriate bonegrowth promoting substance. A syringe 206 filled with a suitablesubstance 207 is positioned with its needle 208 inserted throughaperture 202. As syringe 206 is operated, substance 207 fills implant200 with the bone growth promoting fluid, as can be seen clearly in FIG.15B. FIG. 16A shows implant 200 in position between adjacent vertebrae210, 212 while syringe 206 injects growth substance 207 into theimplant.

A drill bit 216 is shown in FIG. 16B which may be used to createaperture 202 in implant 200. Bit 216 contains a smooth cylindricalsection 216 a, a fluted end 216 b having a point for drilling, and acollar stop 216 c. Drill bit 216 is particularly suited for drillingaperture 202 into implant 200, as collar stop 216 c acts to prevent bit216 from traveling too far into implant 200, possibly damaging thedevice. Drill bit 216 may be helpful when drilling aperture 202 into adevice such as implant 200 a, which has a different shaped structure, ascan be seen in FIG. 17. Aperture 202 can be aligned in any suitabledirection within the device. While aperture 202 can be drilled intoimplant 200 before inserting the device Into position in the spine, itmay be advantageous to drill aperture 202 into implant 200 after it ispositioned between vertebrae 210, 212. This would avoid weakening ofimplant 200, as the device is under compressive forces when in position.Alternatively, implant 200 could be manufactured with aperture 202 inplace in the device.

Bone growth promoting substances can be used in many other arthroplastydevices. FIGS. 18A–B show its use in connection with an artificial discreplacement (ADR) procedure. An ADR device 220 similar to the device ofFIGS. 12A–B contains a pair of extensions 221 for fixing device 220 inthe spine and a pair of end plates 222 a, 222 b each having an aperture223. End plates 222 a, 222 b are separated by an activating structure226. End plates 222 a, 222 b may contain a series of channels which areconnected to apertures 223. When device 220 has been positioned in placebetween vertebrae 210, 212, syringe 206 can be located with needle 208inserted into apertures 223 of end plates 222 a, 222 b to input growthsubstance 207 into device 220 to promote bone ingrowth between thedevice and the vertebrae.

FIGS. 19 to 22A–B depict different arthroplasty devices which can beused in conjunction with bone growth promoting substances to maximizebone ingrowth between the body and the implants. An acetabular componentfor use in hip replacement is shown in FIG. 19. Component 240 is acup-shaped device having a spherical outer surface 242 and a hollowcurved inner surface 244. A front surface 246 contains a plurality ofapertures 248. Apertures 248 are connected to a series of channels whichare connected to a series of outlets 250 which are scattered along outersurface 242 of device 240. When component 240 is placed in positionduring hip replacement surgery, bone growth substance 207 can beinjected into apertures 248 such that the substance can travel throughthe channels to outlets 250, where it can contact the hip bone topromote bone ingrowth between device 240 and the bone. An alternativeembodiment to implant device 240 is shown in FIG. 21. This acetabularcomponent 260 has a spherical outer surface 262, a hollow curved innersurface 264 and a flat front surface 266. Along the periphery of surface266 a series of grooves 268 are channeled into outer surface 262.Grooves 268 may be parallel channels along outer surface 262, or theymay spiral around outer surface 262. When component 260 is positioned inthe bone during hip surgery, growth substance 207 may be injected intogrooves 268 such that the fluid can flow between component 260 and thebone to promote bone ingrowth.

Examples of the present invention for use with femoral components areshown in FIGS. 20 and 22A–B. Referring now to FIG. 20, a femoralcomponent 280 is shown having a body 282 having an outer surface 283, aflat top surface 284, and an outwardly extending stem 286. A pluralityof apertures 288 are located on flat surface 284.

A series of channels within body 282 are connected to apertures 288 atone end, while the other ends are connected to a series of outlets 290located on outer surface 283. When component 280 is implanted inposition within a femur, bone growth substance 207 is injected intoapertures 288 such that it will travel through body 282 and exit throughoutlets 290 between component 280 and the bone to promote bone ingrowth.Alternative versions of this device are shown in FIGS. 22A–B. In FIG.22A, femoral component 280 a contains a body 282 a having an outersurface 283 a, a flat top surface 284 a, and an outwardly extending stem286 a. Along the periphery of surface 284 a, a plurality of grooves 292are channeled into the outer surface 283 a. Grooves 292 may be straightalong outer surface 283 a, or they can spiral around component 280 a.When component 280 a is fixed in place within a femur, growth substance207 can be injected into grooves 292 such that the fluid can flowbetween the implant 280 a and the bone to promote bone ingrowth. FIG.22B shows a similar device 280 b, except that grooves 294 are equallyspaced around the periphery of upper surface 284 b and are oriented in aparallel fashion along outer surface 283 b.

The principles of the present invention taught in FIGS. 19–22B can beapplied to other prosthetic devices such as knee replacements, shoulderreplacement, and spinal fusion cages.

FIGS. 23A–D teaches several alternative embodiments of the presentinvention for use in spinal procedures similar to those taught in FIGS.12A–B and FIGS. 18A–B. Referring now to FIG. 23A, there is shown aspinal device generally indicated at 300 having a pair of end plates 302a, 302 b. Each end plate contains a keel-like fixation component 304which is fixed for rotation about a pivot 306 through the interior areaof the end plate. Component 304 are offset from each other with respectto device 300 such that component 304 rest side by side between endplates 302 a, 302 b when device 300 is in the unactivated position. Thisorientation allows for larger fixation components to be used in device300 for better fixation in position between vertebrae. An activatingcomponent 308 is shown alongside device 300. Component 308 consists of apair of spherical pusher plates 310. In operation, activating component308 is forced between end plates 302 a, 302 b, causing fixationcomponents 304 to rotate about pivot points 306 outwardly through endplates 302 a, 302 b, to extend from device 300 and holding the devicefirmly between vertebrae of the spine, as is shown in FIG. 23B.

FIGS. 23C–D show spinal device 300 a in which slots 316 are incorporatedinto end plates 302 a, 302 b such that fixation components 304 restwithin slots 316 when device 300 a is in the unactivated state. Slots316, which may be shaped such that the end of each fixation component304 just fits within said slot, or may extend along a longer portion ofeach end plate, to allow for the use of a larger fixation component withdevice 300 a, improving the holding power of spinal device 300 a whenpositioned between vertebrae.

FIGS. 24A–D show an alternative embodiment for an arthroplasty deviceaccording to the present invention for use in hip surgery. Referring nowto FIGS. 24A–C, there is shown a device 329 having a femoral component330 with a outwardly extending stem 332, and a hollow passageway 334extending through the central area of component 330. Passageway 334 issquare shaped in this embodiment, but it may be shaped in anyconfiguration in which a component inserted into said passageway cannotrotate, such as an ellipse, a triangle, pentagon, or hexagon. Component330 also contains a recess 336 on its upper surface. Passageway 334 andrecess 336 are connected by a channel 338. An attachment component 340contains an upper section 342 having a square shape with a threadedaperture 344 at its upper end and a lower threaded cylindrical section346. A screw 348 is also provided with the device.

To install femoral component 330 into a femur in a hip replacementprocedure, the inner surface of femur 20 is threaded at the proper depthusing a tool similar to that shown in FIG. 5A. Attachment component 340is installed within femur 20 by threading section 346 into the femur.Component 330 is then located upon upper section 342 of attachmentcomponent 340 by matching the shape of section 342 with recess 334 inthe proper orientation. Screw 348 is then inserted into recess 336 ofcomponent 330 through channel 338 and threaded into aperture 344 to holdthe device in its proper position within femur 20. This procedure“pulls” the device into the femur, helping to prevent fracturing thebone. A torque wrench may be used to adequately tighten screw 348 to itsproper tightness to prevent splitting femur 20. Attachment component 342may be composed of a polymer such as carbon fiber, or alternatively maybe composed of a resorbable material. Device 329 minimizes motionbetween the implant and bone, as the matched shape connection betweenpassageway 334 and upper section 342 of attachment component 340 allowsfor virtually no movement.

An alternative attachment component 340 a for component 340 is shown inFIG. 24D. Component 340 a contains a similar upper section 342containing a threaded aperture 344; however, lower cylindrical threadedsection 346 a contains a hollow internal section 352. Hollow section 352gives threaded section 346 a more flexibility than a solid component.Hollow threaded components and polymer threaded components are lesslikely to cause thigh pain from excessive stress transfer to the femurat the level of the threaded component. Furthermore, resorbablecomponents, in particular, are less likely to cause stress shielding ofthe proximal femur.

FIGS. 25A–B show an embodiment of the present invention for use in aprosthetic knee device. Device 400 includes a cylindrical component 402having a threaded outer surface and a recess 404 having a threaded innersurface. An articulating component 406 includes a planar section 408having an extension 410 with a treaded end 412.

To install device 400, the internal surface of tibia 416 is threadedinternally using a device similar to that shown in FIG. 5A at thedesired depth. Component 402 is then threadably engaged within tibia416. Articulating component 406 is then threadably affixed to component402 by threading end 412 of extension 410 into recess 404 until surface408 contacts tibia 416.

Referring now to FIG. 25B, prosthetic device 420 includes a cylindricalcomponent 422 having a threaded outer surface and an aperature 423having a threaded inner surface, and an upper component 424 having aplanar surface 426 and an aperture 428 in the central region. The uppersurface of component 424 is sized such that a cover 430 may be snappedinto position on the upper surface. Cover 430 may be constructed ofpolyethylene. A bolt 432 having a head 433 is also included with device420.

To install device 420, the internal surface of tibia 416 is threadedinternally using a device similar to that shown in FIG. 5A at thedesired depth. Upper component 424 is placed on the upper surface oftibia 416 and bolt 432 is placed through aperture 428 and is threadedinto aperture 423 of component 422 until head 433 contacts the uppersurface of component 424. Cover 430 is then snapped into position oncomponent 424.

In FIGS. 25A–B, components 402 and 422 may be composed of metal or apolymer, or could also be made from a resorbable material. Components406 and 429 may be constructed from titanium or chrome cobalt.

FIG. 26 shows a device 444 embodying the present invention for use intreating the hip socket. In this embodiment, a fracture 450 of a femur451 is shown at the base of the femoral head 452. Device 444 includes afemoral repair component 453 consisting of a cylindrical member 454having a threaded end section 456. Component 453 also contains anaperture 458 which is oriented angularly toward femoral head 452.Aperture 458 may be threaded internally. A second component 460 ofdevice 444 consisting of a connecting rod 461 having a threaded end 462is connected to femoral head 452 by a threaded aperture 464 withinfemoral head 452.

To install device 444 for repair of the fractured femur, threaded endsection 456 is located within femur 451 using the techniques previouslydiscussed. The correct angular position of component 460 relative tocomponent 453 and femoral head 452 is determined, and threaded end 462is affixed within femoral head 452. Rod 461 is sized such that the endcan be inserted into aperture 458 of component 453 using a small amountof force to overcome the friction fit between the components. Rod 461 isthen inserted into aperture 458 until femoral head 452 is positionedagainst femur 451. The interaction between rod 461 and component 453acts to hold head 452 in the correct position to heal.

FIGS. 27A–B show an embodiment of the present invention for use inrepairing a fracture of the distal end of the femur. Repair device 480includes a component 482 having a solid first section 484 with athreaded outer surface and a narrower cylindrical second section 486. Toinstall repair device 480, the internal surface of femur 488 is threadedat a section on the opposite side of fracture 490 from distal end 492 offemur 488 using a device similar to that shown in FIG. 5A. Threadedsection 484 of component 482 is affixed within femur 488 such thatsection 486 is spaced apart from distal end 492 of femur 488 when thetwo sections of femur 488 are held together tightly along fracture 490.A hole 496 is then drilled across the distal end 492 of femur 488,passing through section 486 of component 482. A screw 498 is then placedinto hole 496, passing through section 486 of component 482 and isthreaded into femur 488 as shown at 500. This device holds the sectionsof femur 488 tightly together to aid in the healing process. Threadedsection 484 can be made from a resorbable material, non-resorbablepolymers, metal, or a combination of materials. For example, section 484could be made with a metal core surrounded by a resorbable component.

The device 480 a of FIG. 27B is similar to device 480 shown in FIG. 27Aexcept for the design of component 482. Component 482 a is constructedlike the component shown in FIG. 24D in that first section 484 a ishollow with a threaded outer surface. As discussed previously, thehollow section allows more flexibility than a solid component. Theinstallation of device 480 a follows the same methods of that taught fordevice 480.

FIGS. 28A–C show a fixation device 500 for use in long bones. Referringnow to FIG. 28A, a first component 502 contains a solid cylindricalportion 504 having an outer threaded surface 506, and a cylindricalportion 508 having a lesser diameter than portion 504 and containing athreaded portion 510 located along its length. A second component 512comprises a cylindrical disc having a threaded outer surface 514 and acentral aperture 516 which is threaded. In addition, a pair of screws520 are provided.

Fixation device 500 is shown on its installed position in FIG. 28B. Along bone 540 is shown having a fracture 542. Threads are made on theinternal surfaces of bone 540 in the appropriate positions in the mannerpreviously described. Component 502 is then positioned within the uppersection 540 a of bone 540 by engaging outer threaded surface 506 intothe threaded position in section 540 a to fix component 502 in itsproper location. Component 512 is then positioned onto threaded portion510 of cylindrical portion 508 while component 512 is being threadedinto lower section 540 b of bone 540. Component 512 is rotated until itis firmly coupled to both component 502 and bone 540. In thisembodiment, left handed threads may be used for threaded 510 and alsofor threaded outer surface 514 and threaded aperture 516. In thismanner, the action of installing component 502 of device 500 acts topull the components together. After device 500 has been installed inbone 540, holes may be drilled into upper section 540 a and lowersection 540 b through the upper and lower ends of component 502 andscrews 520 inserted to prevent rotation of long bone 540 about device500.

FIG. 28C shows device 500 installed within long bone 540 without the useof screws 520.

Another embodiment for use with the arthroplasty devices according tothe present invention involves the use of bone cells. Bone and bonecells are grown onto the prosthesis prior to implanting the device intoa patient. To accomplish this task, bone cells are initially harvestedfrom a patient. Osteoblasts could be harvested from a patient's iliaccrest; a piece of iliac crest bone could be surgically removed. In“Culture of Animal Cells” by R. Ian Freshney, Wiley-Liss New York 2000,which is incorporated herein by reference, techniques for harvestingosteoblasts are described on pps. 370–372. Also described in the articleare cell culture techniques. U.S. Pat. No. No. 6,544,290, which issuedon Apr. 8, 2003, to Lee et al, which patent is hereby incorporated byreference, teaches a method culturing cells onto a resorbing calciumphosphate material. The present invention contemplates the culturing ofcells onto arthroplasty devices made of titanium, chrome, cobalt,ceramic, or other non-resorbable materials.

In the present invention, bone is harvested from a patient, and the bonethen treated to remove the cells. The cells are cultured and grown ontothe prosthesis in a lab. The device, now covered with living bone cells,is subsequently implanted into the patient. These cells, which includeosteoblasts, osteocytes, donor bone cells, stem cells or otherpluripotential cells, and other cells that are capable of transforminginto osteoblasts or osteocytes, will promote the bone ingrowth toimprove the stability of the device in the body. Alternatively, the bonecells could be added to the device at the time of surgery.

To foster the improved bone ingrowth, the titanium components would havesurface treatments. For example, the surfaces could be porous, beaded,plasma sprayed, or covered with fibrillar wire to promote ingrowth.Alternatively, the cells could be cultured onto arthroplasty devicesmade of other metals, or materials such as ceramic and hydroxyapatitecoated metals. In addition, to attempt to improve the ingrowthcharacteristics of this process, bone growth promoting substances suchas TGF-α,-β1, -2; EGF, IGF-I; PDGF, FGF, BMP-1, VEGF and other similarsubstances may be added to the cell culture medium.

It is contemplated that features of the various embodiments may becombined. For example, the expandable component taught in FIGS. 8A–Bcould be used with the threaded component of FIGS. 2–7. Also, althoughthe drawings are directed primarily to the use of the invention inprosthetic hips, the principles may be applied to other prostheticjoints, such as knees, shoulders, ankles and wrists. In addition, bonecells harvested from the patient could be added to the bone growthpromoting substance used in other embodiments. These cells could also becombined with a cell culture media or a synthetic matrix.

While the present invention has been shown and described in terms ofpreferred embodiments thereof, it will be understood that this inventionis not limited to any particular embodiment, and that changed andmodifications may be made without departing from the true spirit andscope of the invention as defined in the appended claims.

1. An arthroplasty device for implantation into a bone, comprising: adisc having a threaded outer surface capable of threaded engagementwithin the interior surface of a bone; a resorbable material, having anouter surface capable of threaded engagement within the interior surfaceof said bone, contacting said disc; a sleeve having an inner opening andan outer surface, containing at least one section contacting the bonehaving a textured surface to promote bone ingrowth, sized to fit tightlywithin the bone; and a prosthetic component comprising an elongatedshank having an outer surface extending between a proximal end and arelatively narrow distal end; wherein when said distal end of saidprosthetic component is inserted through said sleeve in said bone, saiddistal end contacts said resorbable material to support said componentto decrease stress on said textured surface of said sleeve while saidmaterial resorbs.
 2. The device of claim 1, wherein said resorbablematerial comprises collagen.
 3. The device of claim 1, wherein saidresorbable material is selected from high molecular weight poly-L-lacticacid (PLLA) polymers, calcium hydroxyapatite, tricalcium phosphate, andpolydiaoxanone (PDS).
 4. The device of claim 1, wherein said disccontains a drainage through hole.
 5. The device of claim 1, wherein saidtextured surface of said bone contacting section of said sleevecomprises an array of beads.
 6. The device of claim 1, wherein saidtextured surface of said bone contacting section of said sleevecomprises an array of fibrillar wires.
 7. The device of claim 1, whereinsaid textured surface is coated with a bone growth promoting material.8. The device of claim 7, wherein said bone growth promoting materialcomprises bone morphogenetic protein (BMP).
 9. The device of claim 1,wherein said device is implanted into a femoral bone.